1. Field of the Invention
This invention relates to image pickup apparatus and, more particularly, to image pickup apparatus in which the aperture size and shutter time are determined by the brightness of an object to be photographed.
2. Description of the Related Art
As the image pickup apparatus for converting an object image to an electrical signal, there are known electronic cameras and video cameras. In such apparatus, in general, an exposure constant that is obtained on the basis of information of the object brightness from the light metering circuit to determine the exposure, for example, an aperture size of the lens and a shutter speed, can be set automatically or manually.
In such conventional image pickup apparatus there are many which compute proper aperture information (AV value) and shutter time information (TV value) corresponding to the brightness information by a central processing unit (CPU) and display this information on the display device.
The graphic representation of the relation of these AV and TV values determined from the brightness information is usually called "program line diagram". And, the conventional image pickup apparatus is constructed in such a way that this program line diagram is previously memorized in memory means and the AV value and TV value corresponding to the brightness information obtained from the light metering circuit can be read from the memory means.
Also, conventionally the image pickup apparatus of this kind performs recording of the image information picked up with the thus set aperture and shutter time on a recording medium.
As this recording method, there are known the frame recording method in which the image information of one frame is recorded by division to a plurality of field informations and the field recording method in which the image information of one frame is recorded as field information. In the above-described image pickup apparatus, either the field recording method or the frame recording method is employed.
However, the conventional apparatus may be modified so that the frame recording and field recording are performed by one apparatus component. Nevertheless there was a problem in that even if the shutter time and the aperture value were set on the basis of the brightness information, it was under the same setting condition that the quality of the picked-up image differed between the field recording and the frame recording.